Yahoo SMTP Server: Delivery Temporarily Suspended

Recently the outgoing messages to Yahoo from my Linux boxes are all deferred. The linux box hosts a website which contains a webform, which sends about 200 mails to 100 subscribed accounts, which is about 20K messages per day. About 13 accounts are Yahoo addresses. I use Postfix and below is the results from “mailq”.7AE4531F83EE 1895 Fri Apr 5 22:08:17 apache@myhostname(delivery temporarily suspended: lost connection with mta7.am0.yahoodns.net[66.196.118.35] while performing the HELO handshake) xxxx@yahoo.com

Tried to telnet to port 25 of Yahoo’s SMTP server, and this is the message:421 4.7.0 [TS02] Messages from xx.xx.xx.xxx temporarily deferred – 4.16.56.1; see http://postmaster.yahoo.com/errors/421-ts02.htmlConnection closed by foreign host.
Contacted Yahoo using two online forms: